ChIP-Seq: Cells were cross-linked with 1% methanol-free formaldehyde in fresh medium for 10 minutes. Cross-linking reaction was quenched with glycine at a final concentration of 0.2M. Cells were then washed twice with ice-cold PBS and harvested. Cell pellets were then resuspended in LB1 buffer (50 mM Hepes–KOH, pH 7.5; 140 mM NaCl; 1 mM EDTA;10% Glycerol; 0.5% NP-40 or Igepal CA-630; 0.25% Triton X-100, protease inhibitors) for 10 minutes at 4°C, pelleted and resuspended in LB2 buffer (10 mM Tris–HCL, pH8.0; 200 mM NaCl; 1 mM EDTA; 0.5 mM EGTA, protease inhibitors) for 10 minutes at 4°C. Cells were pelleted, resuspended in LB3 buffer (10 mM Tris–HCl, pH 8; 100 mM NaCl; 1 mM EDTA; 0.5 mM EGTA; 0.1% Na–Deoxycholate; 0.5% N-lauroylsarcosine, protease inhibitors) and sonicated using Misonix Sonicator 3000. After addition of Triton-X to a final concentration of 1%, the lysate was centrifuged at 20,000g for 10 minutes to pellet debris. Sonicate chromatin was then added to the bead-antibody complexes and incubated overnight at 4°C. Bead-antibody were prepared as follows: Protein G-coupled Dynabeads were incubated overnight with primary antibodies (anti-H3K9me2; Abcam ab1220) in PBS added with 5 mg/ml BSA. Beads were washed extensively with RIPA buffer (50mM HEPES pH 7.6, 1mM EDTA, 0.7% Na deoxycholate, 1% NP-40, 0.5M LiCL), once with 1x TE buffer and eluted in 200ul of buffer containing 1% SDS and 0.1M NaHCO3. Cross-linking was reversed by incubation at 65°C overnight, followed by RNase A treatment at 37°C for 1 hour and Proteinase K treatment at 55°C for 2 hours. DNA was then extracted using Beckman Coulter's Agencourt RNAdvance Cell v2 kit following the manufacture’s instructions. Eluted DNA was then used to perform ChIP-Seq library preparation using the MicroPlex Library Preparation Kit v2 (Diagenode)